This proposal seeks to become a part of the INIA consortium "Neurobiologial Basis of Excessive Drinking", and focuses of the neuropeptide Urocortin 1 (Ucn1). Ucn1 is the most effective endogenous ligand of both corticotropin releasing factor (CRF) receptors CRF1 and CRF2. The main source of Ucn1 in the brain is the non-preganglionic Edinger-Westphal nucleus (npEW). One of the main projection areas of npEW is the lateral septum (LS). Recent evidence indicates that the Ucn1 system is extremely sensitive to alcohol, that differences in this system predispose animals to differences in alcohol consumption, and that manipulations of this system regulate alcohol intake. Based on this evidence we hypothesize that differences in Ucn1 activity are important determinants of excessive alcohol intake. In this project we propose to apply collaborative efforts to investigate three specific aims: (1) To identify genes showing consistently different expression in npEWand LS between selectively-bred high and low alcohol consuming animals using microarray technology. Following animal models will be explored: mice selectively bred for excessive drinking in the dark, mice selectively bred for excessive drinking in the scheduled fluid access procedure, mice selectively bred using the 2-bottle choice procedure, rats selectively bred using the 2-bottle choice procedure, and their respective control lines. Differences in gene expression will be confirmed using immunohistochemistry, in situ hybridization and quantitative RTPCR. (2) To test alcohol consumption in Ucn1 knockout mice using three behavioral models: DID - excessive drinking in the dark;SHAG - excessive drinking due to scheduled access;and the standard 2-bottle drinking procedure. We will also use microarray technology to investigate whether Ucn1 knockout mice developed compensations in genes identified in Specific Aim 1. (3) To test whether genes identified in animal models of excessive alcohol consumption in Specific Aim 1 and Specific Aim 2 are expressed in npEW and LS of human post-mortem brains, and whether they are differentially expressed between alcoholic subjects and controls. Human homologues of the identified genes will be tested by quantitative RT-PCR. Taken together, these studies will provide a thorough comprehensive analysis of the Ucn1 neurocircuit and its involvement in excessive alcohol consumption, and could provide groundwork for development of new approaches for Oregon Health treatments of alcoholism and alcohol abuse disorders.